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    Subject[PATCH V6 0/6] Fast mmio eventfd fixes
    Date
    Hi:

    This series fixes two issues of fast mmio eventfd:

    1) A single iodev instance were registerd on two buses: KVM_MMIO_BUS
    and KVM_FAST_MMIO_BUS. This will cause double in
    ioeventfd_destructor()
    2) A zero length iodev on KVM_MMIO_BUS will never be found but
    kvm_io_bus_cmp(). This will lead e.g the eventfd will be trapped by
    qemu instead of host.

    1 is fixed by allocating two instances of iodev and introduce a new
    capability for userspace. 2 is fixed by ignore the actual length if
    the length of iodev is zero in kvm_io_bus_cmp().

    Please review.

    Changes from V5:
    - move patch of explicitly checking for KVM_MMIO_BUS to patch 1 and
    remove the unnecessary checks
    - even more grammar and typo fixes
    - rabase to kvm.git
    - document KVM_CAP_FAST_MMIO

    Changes from V4:
    - move the location of kvm_assign_ioeventfd() in patch 1 which reduce
    the change set.
    - commit log typo fixes
    - switch to use kvm_deassign_ioeventfd_id) when fail to register to
    fast mmio bus
    - change kvm_io_bus_cmp() as Paolo's suggestions
    - introduce a new capability to avoid new userspace crash old kernel
    - add a new patch that only try to register mmio eventfd on fast mmio
    bus

    Changes from V3:

    - Don't do search on two buses when trying to do write on
    KVM_MMIO_BUS. This fixes a small regression found by vmexit.flat.
    - Since we don't do search on two buses, change kvm_io_bus_cmp() to
    let it can find zero length iodevs.
    - Fix the unnecessary lines in tracepoint patch.

    Changes from V2:
    - Tweak styles and comment suggested by Cornelia.

    Changes from v1:
    - change ioeventfd_bus_from_flags() to return KVM_FAST_MMIO_BUS when
    needed to save lots of unnecessary changes.

    Jason Wang (6):
    kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd
    kvm: factor out core eventfd assign/deassign logic
    kvm: fix double free for fast mmio eventfd
    kvm: fix zero length mmio searching
    kvm: add tracepoint for fast mmio
    kvm: add fast mmio capabilitiy

    Documentation/virtual/kvm/api.txt | 7 ++-
    arch/x86/kvm/trace.h | 18 ++++++
    arch/x86/kvm/vmx.c | 1 +
    arch/x86/kvm/x86.c | 1 +
    include/uapi/linux/kvm.h | 1 +
    virt/kvm/eventfd.c | 124 ++++++++++++++++++++++----------------
    virt/kvm/kvm_main.c | 20 +++++-
    7 files changed, 118 insertions(+), 54 deletions(-)

    --
    2.1.4



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